Peristaltic pump



March 6, 1951 B. G. COPPIN G PERISTALTIC PUMP Filed June 15, 1946 IN VEN TOR.

c H GM 5 w m 5. Y O B Patented Mar. 6, 1951 PERISTALTIC PUllIP Bruce G.Capping, Fulton County, Ga, assignor to The Coca-Cola Company,Wilmington, Del., a corporation of Delaware Application June 15, 1946,Serial No. 676,929

13 Claims. 1

This invention relates to pumps, and more particularly to a new andimproved peristaltic pump.

Heretofore, sundry devices of this general type have been proposed, suchgenerally contemplating the use of a block of rubber or rubber tubewhich is in some manner alternately compressed and extended to exert apumping action on fluid contained in an opening or passage in, oradjacent the rubber element, the purpose of such pump being to eliminatethe close machining, tight seals and multiplicity of partscharacterising pumps of the gear displacement type. Unfortunately,however, it does not appear that these pumps have been commerciallysuccessful, the rubber therein usually wearing out at a rate which makesthem impractical for any prolonged use. The chief factor in this wear isthat of heat, and accordingly, it has been necessary to resort toexpensive gearing down if such pumps are to be at all usable, theproviding of speed reducing apparatus entailing additional cost andresulting in limited transfer of the fluid being handled.

An object of my invention is to provide a peristaltic pump whichconsistently operates at high speeds with small, inexpensive motors ofstandard design.

Another object is to provide longer life in such a device.

Another object is to make possible a wide variety of operatingcharacteristics including those of high discharge pressure, and very lowsuction pressure in such a pump.

in Fig. l, the right half of the pump being shown in verticalcross-section; and

7 is an outside mounting ring, the two co-operating A still furtherobject is to provide simplicity of construction and therefore cheapnessof manufacture in a peristaltic pump.

Another object is to make possible economy of operation of sucha device.

Another object is to provide ready accessibility to the parts of such apump which are most'likely to wear, thereby facilitating repairs whensuch are necessary.

Another object is to provide self-sealing means in a pump of the instanttype.

Another object is to provide an automatic safety valve in a peristalticpump.

These and other objects made apparent through the further progress ofthis specification are accomplished by means of my peristaltic pump, afull and complete understanding of which is facilitated by reference tothe drawing herein in which:

Fig. 1 is a view in side elevation of the pump mounted on a motor, theupper half of the pump being illustrated in vertical cross-section;

Fig. 2 is an end elevation of the pump shown in a manner explainedhereafter. I4 is an innerring assembly consisting of a sleeve andinnerfiange l5, and a press on outer-flange l6, and Ilia. is an innersleeve which is bonded strongly to the inner diameter of rubber elementII. I! isan eccentric, mounted in conjunction with eccentric bearing [8.Elements l9 are main fastening screws holding together the pumpassembly.

20 is the end-bell of a motor 2|, to which the pump proper is attachedthrough mounting screws 22. 23 indicates the motor shaft, which ispositioned in operative relationship to motor shaft bearing 24.

A tension relief hole 25 is cored through the rubber pumping element II, the function and operation of which aperture will be explained indetail at a later point in the instant specification.

26 is an inlet port through which a fluid (either liquid or gas) entersthe pump proper, and 21 is the outlet port through which such fluid isejected after having passed through and been boosted by the pump.

28 is a blow-by barrier, which will also be described and explained at alater point herein.

In assembling my peristaltic pump, stator ring it], rubber pumpingelement II, with the associated sleeve Ilia; inside mounting ring l2,and outside mounting ring [3, are clamped together into an assembly bymeans of the four main fastening screws l9. The relative dimensions ofthese parts are such that when the assembly is made, the inside mountingring l2 and the outside mounting ring l3 serve to tightly clamp thepumping element l I hermetically to the stator ring III. In thisconnection, it will be noted that elements l2 and I3 are providedwithsloping faces I20. and [3a, which mate with corresponding sloping faceson element i l, and as the assembly is pulled together not only is saidrubber element pressed inwardly and sealed against stator ring ill, butit is also drawn outwardly against such ring. This wedge action has theadvantage of not only providing a more secure seal, but it also preventsany inward displacement of the rubber resulting from the squeezing-upaction of the pumping operation.

Inner assembly 14 is likewise firmly clamped to the inner periphery ofrubber pumping element II, this clamping being eifected by having theouter flange l8 form a press fit on the sleeve l5, said outer flangebeing pressed on .to said sleeve with sufficient force as to givethedesired clamping action against the inner periphery of pumping :pump;and to its.continued-life- -tnat the fastening of the pumping elementtothe stator and to i3the1inner rmgassembly 14, be very secure; and

the means illustratedin the drawingfor accom- 1 'plishing this resultare by mechanical clamping.

. Such; clamping may. be supplemented, however, by bindingorgcementingpthe rubber, to all adjoiningmetal parts, or itispracticalinsome ap- :plication, to substitute cementing or bonding.material .for the; mechanical clamping ,method which. is .shownthereinfor illustrative purposes.

Advantages of .the instant arrangement lie in readydissembly, of .thepump and replacement of .anyworn .or broken.v part in a minimumof 1time. Life tests to .date indicate, however, that replacementofanypartsis likely toberequired at infrequent intervals.

. Continuing further 1 with :the instant assembly,

bearing its is pressed into the sleeve and inner flange .l5,.and in turneccentric llis fitted into the innerdiameter of said eccentric bearing,the

eccentric, itself, being mounted on the end of motor. shaft .23.Hence,-it-is apparent that when said motorshaft rotates the eccentricll,.act

ing through its associated bearing-willcause theinnerringiassemblyitogenerate an eccentric motion, and since lthe -inner ring assembly isrigidly .fastenedto the inner periphery-:ofthe pumping. element H sucheccentric motion is iandmust-be translatedto the inner-part of saidelasticcement ll.

-In this connection-reference is now specifically directed toFig. 3 ofthe drawing, where-itwill be seen that the eccentricmotion'of the innerpart of the rubber pumping element will result inthe .inside pumpingface of saidelement II ,beingautomatically drawn away from and then-;pressed against the-pumping face =-30 of the .stator ring 10. It'-isfurther apparent that; due to the eccentric nature of the motion, thissqueezing action between the rubberand metal .pumping .faces willadvance progressively and .rotatively in thedirection-of the rotation ofthe .motor,: as suggestedby-the arrow on -Fig.-2-0f-the idrawing; thussetting up a peristaltic action which results in a'fluid being-drawninto the device through inlet port 26 and carried around anddischargedthroughoutlet port 21.

Referringagainto-Fig. 3, it will be noted that the pumping face ofthe'rubberelement, when notdistorted-in either direction by theeccentric,

is flat; and deflection accordingly takes placein bothdirections fromthe flat position shown by wtheisolid line of the drawing. Maximumout-=..ward deflection is suggested -by the' curveddotted line of the figureand the concave shape of the pumping face 30 of the stator ring i is sodimensioned that it permits a full inward defiection of the pumping face29 of H, minus a small factor which is provided to allow the rubber tosqueeze up tightly against the pumping face 38 of ring I0. This concaveshape of the pumping face of the stator .ring is important, in that itincreases thecross-sectionatarea of the opening very substantially,thereby increasing xthe capacity of the pump; and what is possibly.moreimportant, also permits the inward deflection of the rubber withoutundue distortion '..thereof. This factor, resulting in reduction ofheat, and-hencein greatly increased life of the rubber-elementand thepump itself.

Consideration is now directed to the specific shape of said pumpingelement II, it being apparent that the portion 3! thereof which formsthe base and stem of the Y suggested heretofore siderableimportance.

is,;.provided: witha ina-rrowed; sectiom 32, and the width; across.:thispection; relativeqto the Width of ;;pumping -,f-ace' 29. and to thewidth of, the rubber ..;;gripped in thfigillllG]? ring assembly M isofcon- The width .Of said nar- ,-row;section';,32 =is; preferably slightlyless than that I of; :the, pumping, face .129; so; that zwhentheeccentric draws. the rubber. away from .this point ,as; establishedwhen.the element; is; in. a fneutral position, the ;motion is :taken up,in-,-the bending :of therubber at the outeredgesgof .the pumping rface,=.;and little-actual stretchingmfthe, rubber 1 accordingly ,-.ocours.Upon; analysis, :it .will 1 be cseencthat;if. se.ction;:32 -':were. madeas wide or wider :than :the :pumping ,fa,ce,.x-:it; would -mean1.,that,,;there:wo111d 'occuna, stretchingof the rub- ;bce itself;atithe.outsideedges, iresultingiboth in ,.--severe; stress;- on; the;rubber itself, .and' .on the ;-:connectionpbetween therubbenand statorring 4 2 :llL-withundesirable iheat and-:wear.. consequences aspointedoutsheretofore.

IlilhflSzBlSObBBILfOllIld possibleto control the -gmaximumpumpingpressuresof the pump by controlling-.sthe width. of .:this .narrowsection 32 'relative to;the.;width...of :the pumping face. JFcr example,it will be seen that if said neckssection :.-.:is made Very: .narrow, 1as icompared with the pumping face, there will be areas atthe outeredgerofysaid face-.where the :rubber. does not have ;the,direct.pressureof .athe eccentric squeezing it eagainstxthe pumping face-filliof. thestator ring,

and when this occurs;thepnly-resistance -to a .cbackward'zfiowiorleakage of. the liquid or gas ibeing .handleclzbycthezpump isby virtueof the 5 hardness or elasticity 20f l-the rubber itself. By

warming; the Widthc'Of: section: 32 and byusing rubbers of varioushardness and elastic charac- ;ter.is tics,:. .ithas been foundpracticable to build -:pumps .which azwill .idevelop pre-determinedmaximum. pressures at which pressures the fluid being pumped overcomesthe resistance-of the .:-.rubbers..at: ithesouter edges Y of thepumping" surfaces and blows -by,-,thus creating an automatic.zsafetyrvalve in the-purnp by-means of which it protects itself-.against"destruction in the event .of a blockage of discharge.

The widthof 'theinner periphery, of the rubber pumping element which-isclamped toqthe iinner ring assembly 14' ismadewider than the width ofsection 32. This isan important feature in that it provides for aslight; flexing of -that part of- -the-rubber which is clamped in theinner ring assembly, which 'fiexinghas .been found essential ginpreventing relative motion "between "the'flanges of said inner ringassembly and that portion of the pumping element II which they grip. Anysuch relative motion between the inner ring assembly and the rubberpumping element results in a rapid wearing away of the rubber, andaccordingly, the peculiar cross-sectional shape of the pumping elementas described herein and arrived at only through considerableexperimentation and research, is of great importance in securing a pumpof satisfactory characteristics, including particularly, but not limitedto long life.

Finally, it will be noted that adjacent to the points where element IIis gripped by surfaces I511 and Heb, there is formed generally circularcut-out portions 32a which provide relief pockets at these points intowhich the rubber of base member 3!, and to a lesser degree narrowedsection 32, may displace durin the pumping operation, this having beenfound desirable in preventing wear at these points.

.A blow-by barrier 28 (Fig. 2) is provided between the inlet and outletports, the purpose of this barrier being to prevent fluid from shortcircuiting across between the inlet and outlet and negativing theeffectiveness of the pump. Said barrier 28 is provided by formingelement H with a wedge-like rubber projection which fits snugly into acomplementary notch formed in the inner surface of stator ring l0, andwhen the assembly is clamped up the squeezing action of the insidemounting ring i2 and the outside ring l3 causes the rubber to expand inthe barrier notch, thus effecting a hermetic seal against undesiredshort-circuitin of fluid.

A tension relief hole 25, which is also an important feature of theinstant pump, is made necessary by the blow-by barrier 28, since at thisparticular point the eccentric motion or the pulling away motion of therubber is firmly resisted by the above described gripping of the barrierin stator ring 10. Tension relief hole 25, however, provides a means foreliminating this direct pull on barrier 28, it being apparent that atthis point, the pulling away motion only results in the deformation ofthe tension relief hole with a consequent relief of stress on thebarrier itself.

It will be noted that a feature of the instant pump resides in the factthat when not running, it is automatically self-sealing, eccentric I!and associated structure so bearing on pumping member H as to alwayspress a portion of the inner face 29 of said pumping member againstconcave face 30 of stator ring l0, thereby effectively blocking andsealing the fluid passage at such point. The advantages of thisarrangement are at once obvious to those skilled in the pumping art, andthe broader field of hydraulics.

From the foregoing, it is apparent that I have disclosed and described anew and unique peristaltic pump which not only will develop a very highpressure on the discharge side, but also a pump having a positivesuction, the weight of the walls of the rubber pumpin element H, coupledwith the forced suction resulting from the pulling away action caused bythe eccentric, making it possible for this pump to draw very highvacuumas for example, in excess of twenty-nine (29) inches of mercury.

That my pump will handle liquids of all viscosities and gases with equalfacility.

That its design is such that the fluid being pumped does not come intocontact with the rotative elements and therefore no expensive orcostly-to-maintain, power-consuming seals are required.

That this pump works with good efficiency at I rotative speeds as highas 3,500 R. P. M., thus permitting direct coupling to small motors ofstandard design.

That a wide range of performance characteristics are made possible in mypump through dimensional changes in the rubber pumping element and/orchanges in the characteristics of the rubber or other material fromwhich this element is fabricated.

That it is possible to design this pump to a maximum operating pressureupon which fluid will simply blow by and thereby act as an automaticsafety valve, this feature making it unnecessary to equip the pump withthe conventional spring-loaded by-pass which is a costly and not alwayssatisfactory feature of many small pumps.

That the instant peristaltic pump is susceptible to extreme cheapness inmanufacture, all

parts being of such a nature that close machining tolerances are notnecessary, it being possible and practical to make all parts of the pumpexcept the eccentric bearing by such economical manufacturin processesasstamping, molding, or die-casting.

While I have disclosed and described herein one embodiment of myinvention, such action is not to be taken as limiting in any way, but onthe contrary is purely illustrative, it being intended that the appendedclaims shall be interpreted, and given a construction and scope fairlyin keeping with my contribution to the art.

I claim:

1. In a device of the character described, in combination, a source ofpower, and a pump operatively engaged therewith, said pump comprising arigid stator ring of generally T-shaped cross-section, a flexiblecircular pumping element of approximate Y-shaped cross-section mountedadjacent said ring, an inner ring assembly securely engaging the lowerportions of said Y-shaped pumping element, an inlet and an outlet forthe pump, and an eccentric engaging said inner ring assembly, movementof the eccentric alternately compressing and expanding the pumpingelement, thereby driving a fluid through the pump.

2. In a device of the character described, in combination, a source ofpower,'and' a pump operatively engaged therewith, said pump comprisingan outer circular stator ring, an inner rubber pumping ring, an aperturein said pumping ring, means for alternately compressing said pumpingelement against the inner surface of said stator ring and drawing saidpumpin element away from said surface, an inlet and an outlet for thepump, and a blow-by barrier formed integral with the pumping element andseating in a notch formed in the inner peripheral dimension of saidstator ring, the barrier automatically disengaging itself from thenotchat a pre-determined pressure, permitting fluid being handled by thepump to blow by a such time.

3. In a device of the character described, in combination, a source ofpower and a pump operatively mounted therewith, said pump comprising acircular metal stator ring of generally T-shaped cross-section, aflexible circular pumpin element of approximate Y-shaped cross-sectiondisposed in sealed relationship with said stator ring, an eccentricpositioned. within 7 sis-aidzimunpingzzelementtand inzcontactitherewith,an inlet and an outlet for the pump, movementmic-the;:eccentricscausing" athe pumping zelement .tobet progressively.zcontracted: and. expanded, .ztherebyzimpellingi a:fiuid through :the;pump.

4. In a device of the characterzdescribed,;in .combination, :7: a.source of ppower, sand a 1: pump :1 pperatively. engagedtherewith,r-said'cpumpr com- -;prising arstator ring of generallyT-shaped crossiazsention -arzrubber:ipumpingtelement; associated.;..therewith,.:said pumping elementhavings an approximate Y-shapedorosse'se.ction-,-'and aneccentrictmounted-hdiaceht said-pumping;element, an :inletzand: anoutletufor;the pump; the movementofithe-=eccentrica;causing:theipumpingielement to heprogressivelylcompressed andexpanded, there- -=by iimpellingea Lfiuidthrough :the pump.

ii 5; In a device of thecharacter described 'in combinatioma'source of-power; and a pump operatively engaged therewith, said pump comprising arigid stator ring, a "-fiexib'le circular pumping element ofapproximateY-shaped cross-section mountedadjacent-said ring, an inner ring assemblysecurely engaging-the lower portions of said Y-shaped pumping element,and an eccentric -operatively-engaging said inner =-ring assembly,an-inlet and an outlet for the ruimninovement of the eccentricalternately compressingand-expandingthe pumping element, thereby drivinga "fiuid through'the pump.

' 6. 'In ahdevice-ofthe characterdescribed, in combination;asource-of-power, and a pump operatively engaged therewith, said pumpcomprising a stator ring; a:flexible circular pumping element ofgenerallyY-shaped cross-section mounted adjacent said ring, an innerring assembly-securely engagingthe lower portionsof said pumping ele-=ment, and an eccentric operatively engaging said *inner'ring assembly,aninlet and an outlet for the pump; movement of the eccentricalternately compressing and expanding the pumping element,therebydriving-afiuid through the pump.

7:111 a-device of the character described, in combination, :a source ofpower, and a pump operatively engagedtherewith, .said pumpcomprisinganouter circularJstator ring, an inner rubber'pumping ring a'tension relief holein saidpumping ring, means, for alternatelycompressing-said pumping element against'the inner surface of saidstator ring and drawing .said 'pumping element a'way 'from'said surface,an inlet 'and'an-outlet for the'pump, and afwedgeshapedblow bybarrierpformed'integral with the "pumping element and seating in a"notch formed inthe inner peripheral dimension'of said stator ring, the?barrier automatically disengaging itself 'fromthe notch atpre-determined pressures, per- 'mittingfluid'being handled bythe pump toblow by atgsuch :time.

.In a device of thecharacter described, in combination, a source ofpower, and a pump -operatively engaged therewith, said pump .com-

prisingyan' outer'circular stator ring, an inner rubber pumping ring,means for alternately compressing said pumping. element against theinner "surface -ofsaid-stator ring and "drawing said pumping elementaway from said surface, an inlet and'an-outlet-for the pump, and,a'blow-by barrier formed integral with the pumping ele- "ment and'seating in' a-notch formedin the inner 5 such :time.

.9. in a--:devic,e of the character described, a rubber peristalticpiston, comprising .a ring of generally v-shapedrcross-section, the:stem of a the -Y= being narrowerthan thezupper arms there- 10 of,;there.-being. sloping anchoring surfacesz-cn said arms ran inletiand anoutlet communicating --with saidipiston'; means; including acentral-eccen- ;fcr.--motivati'ng :said pistonga circular-stator Jllilgsurrounding said-piston, and meansrhermeti- T, cally sealing the-outerperipheralmarginstofv the piston, 1,With the stator ring, said; means.com- 1;prisingitwocasing;halves, and meansfonsecuring -*s'aid :halves.together andzagainst the. outeripedges :;of: said .rubber: piston.

10. In a device-pf thecharacter described, a

--riibberrperistaltic, pumping element,- comprising;a:-ring"of:;genera11y -Y -shaped cross-section, .the rstemgoffthelbeing lnarrowerqthan the upper arms thereof; anzinlet and an outletcommunicating withisaid pumping element,; means including ea; central;eccentric for. motivating said element, arstator ring surrounding s'aid;pumping element .candu being: hermetically sealed thereto, a: groove 1in ,.said: stator ring, and. a: peripheralugroove :in

:.rsaid pumping 1element,,. aid .latter groove :00-

operating with the.- groove. of :the stator ring in pumpingiliquid :by:peristaltic' action.

.. 1 1c- Azflexiblepumping element=for.a peristaltic pump, comprising acircular ring :of generally i-shapedz cross-section, the. stem of the Ybeing narrower rthan .the upper. arms thereof.

12. in. a: device for pumping fluid .bya peristal- -:.tic-like "actiomragrooved flexible pumping ele- ;;.ment, means forisubstantiallydeflecting only the iOzbottonrof the groove. to squeezefiuidprogressively in the groove: and means confining the flexing ofzxthe: pumping elementuto substantially only :the :imme'cliateportionofthe groove"- being acted upon :1 by uz aidz first. mentioned means-during agiven ,;,,-,::.phase..of: thezpumping operation.

:13. In; apdevice tofu the character described, a rubber pumping elementcomprising a circular rubbersring; of generally "Yeshaped cross-section,:a;blowebyloarrier..formed integral .with said ring onrthe; outerperipheral. .edge thereof, and a ieniSiOn mhef! tho-1e formed .inhthe.rpumping :element adjacent said safetybarrier; an inlet and an outv let;.--communicating .with=.:said pumping-element, ;a:nd."i.means1..or..automaticallyv compressing and 55.1distending: said element. to :effectvpumping rby .peristaltioaction,whereby aaxminimum of stressing andzdistending of, said rubber epumping elemerit .isc-present inestablishing and maintaining such action.

IQBRUCE GMCOPPING.

. REFERENCES CITED "The?following-references are of record :in the ifilelofthis patent: (in

1 UNITED STATES PATENTS Number Name Date 765,360 1 Baumann June 24, 19302,246,488 Fraser Junel'l, 1941 2,251,235 Weyde'll July 29, 1941

